Presence of distinct cis-acting elements on gonadotropin gene promoters in diverse species dictates the selective recruitment of different transcription factors by steroidogenic factor-1.
The nuclear receptor steroidogenic factor-1 (SF-1) regulates the cell-specific expression of the pituitary gonadotropin subunit genes. Several potential DNA-binding sites for SF-1, estrogen receptor (ER) and the immediate-early transcription factor NGFI-A are found in LHbeta genes from many species. In this study, we have examined the action and interaction of these transcription factors on LHbeta gene promoters from two representative vertebrate species, i.e. rat and salmon. Cotransfection studies in COS-1 cells have shown that the action of SF-1 on salmon gonadotropin IIbeta (sGTHIIbeta) gene promoter was dramatically enhanced when combined with ER. The rat LHbeta promoter was activated by SF-I or ER individually, but these two factors, however, were unable to act in synergism on this promoter. In contrast, NGFI-A, specifically in cooperation with SF-1, transactivated the rat LHbeta gene expression but was ineffective on the sGTHIIbeta gene. Gel shift experiments showed that this lack of activation was due to the low affinity of the salmon NGFI-A-responsive element for its binding protein. In conclusion, our studies demonstrate that differential recruitment of distinct transcription factors by SF-1 might be a common mechanism to activate the cell-specific gonadotropin gene expression in different species.
Le Dréan
Y
Y
Hospital for Sick Children, Department of Clinical Biochemistry, University of Toronto, Ont, Canada.
Liu
D
D
Xiong
F
F
Hew
C L
CL
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D004357:Drug Synergism; D051766:Early Growth Response Protein 1; D051717:Fushi Tarazu Transcription Factors; D006062:Gonadotropins / Q000235:genetics*; D006367:HeLa Cells; D018398:Homeodomain Proteins; D006801:Humans; D017874:Immediate-Early Proteins; D007986:Luteinizing Hormone / Q000235:genetics; D011401:Promoter Regions, Genetic; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen / Q000235:genetics / Q000502:physiology; D013045:Species Specificity; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D014162:Transfection
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; D051717:Fushi Tarazu Transcription Factors; D006062:Gonadotropins; D018398:Homeodomain Proteins; D017874:Immediate-Early Proteins; C515057:NR5A1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C016844:salmon gonadotropin; C515058:steroidogenic factor 1, mouse; C515060:steroidogenic factor 1, rat; D007986:Luteinizing Hormone